What is it about?

This study proposes the design of an efficient and high-performance system for defect classification by combining well-known machine-learning algorithms: support vector machine, random forest (RF), and k-nearest neighbours. To begin, possible features are designed and feature selection using principal component analysis and RF is investigated to automatically select the most effective features. Then, a hierarchical structure of classifiers is proposed for efficiently adjusting the rates of true defect and fake defect classification. The proposed system is evaluated over a database of 3502 images captured from real OLED display devices in different illumination conditions. The defects in the database are divided into 10 classes corresponding to the types of true defect and fake defect. The experiments confirm that the proposed system can achieve an accuracy of up to 94.0% for the binary classification of true defect and fake defect and an overall recognition rate of 86.3% for the 10 sub-classes.

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Why is it important?

With the rapid growth of organic light-emitting diode (OLED) display devices, the industrial manufacturing of OLED panels is currently an expanding global reality. Regarding quality control, automatic defect detection and classification are undoubtedly indispensable. Although defect detection systems have been widely considered in the literature, classification systems have not received appropriate attention.

Perspectives

This article was produced from an industry-funding project demanded by a world-class company in machine vision business. Even though it studies various visual pattern recognition approaches which were popular before the deep neural networks were widely spread, its results are useful when the amount of sample data is small, which is true in general for machine vision.

Hakil Kim
Inha University

Read the Original

This page is a summary of: Design and evaluation of features and classifiers for OLED panel defect recognition in machine vision, Journal of Information and Telecommunication, August 2017, Taylor & Francis,
DOI: 10.1080/24751839.2017.1355717.
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